Polyamide-imide resin film

ABSTRACT

The present invention relates to a polyamide-imide resin film having a low birefringence index, including: a polyamide-imide block copolymer containing an amide repeating unit to which an isophthaloyl group and an aromatic diamine residue are bonded; an imide repeating unit; and a trivalent functional group containing an aromatic tricarbonyl group.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a 35 U.S.C. § 371 National Phase Entry Applicationfrom PCT/KR2018/015463, filed on Dec. 7, 2018, and designating theUnited States, which claims the benefit of filing date of Korean PatentApplication No. 10-2018-0002877 filed with Korean Intellectual PropertyOffice on Jan. 9, 2018, the entire contents of which are incorporatedherein by reference.

The present invention relates to a polyamide-imide resin film.

TECHNICAL FIELD Background Art

An aromatic polyimide resin is a polymer mostly having an amorphousstructure, and exhibits excellent heat resistance, chemical resistance,electrical characteristics, and dimensional stability due to its rigidchain structure.

Such a polyimide resin is widely used for electric/electronic materials.

However, the polyimide resin has many limitations in use, because it isdark brown due to the formation of a CTC (charge transfer complex) of πelectrons present in the imide chain.

In order to solve the limitations and obtain a colorless transparentpolyimide resin, a method of restricting the movement of the π electronsby introducing a strong electron attracting group such as atrifluoromethyl (—CF₃) group; a method of reducing the formation of theCTC by introducing a sulfone (—SO₂—) group, an ether (—O—) group, or thelike into the main chain to make a bent structure; and a method ofinhibiting the formation of the resonance structure of the π electronsby introducing an aliphatic cyclic compound, have been proposed.

However, it is difficult for the polyimide resin according to theaforementioned proposals to exhibit sufficient heat resistance due tothe bending structure or the aliphatic cyclic compound, and a filmproduced using the same has limitations in that it exhibits poormechanical properties.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an aromatic polyamide-imide copolymerfilm exhibiting excellent mechanical properties while being colorlessand transparent.

There is provided a polyamide-imide resin film, including: apolyamide-imide block copolymer containing an amide repeating unit towhich an isophthaloyl group and an aromatic diamine residue are bonded;an imide repeating unit; and a trivalent functional group containing anaromatic tricarbonyl group, wherein retardation (Rth) in the thicknessdirection measured at a wavelength of 590 nm is 2000 nm or less.

Hereinafter, a polyamide-imide resin film according to an embodiment ofthe invention will be described in more detail.

In addition, according to the present disclosure, a polyimide-based filmincluding the above-mentioned polyamide-imide block copolymer isprovided.

Unless otherwise specified throughout this specification, the technicalterms used herein are only for describing specific embodiments and arenot intended to limit the present invention.

The singular forms “a” and “an” are intended to include the plural formsas well, unless the context clearly indicates otherwise.

The term “including” or “comprising” used herein specifies a specificfeature, region, integer, step, action, element, and/or component, butdoes not exclude the addition of a different specific feature, area,integer, step, action, element, component, and/or group.

Terms including ordinal numbers such as “first”, “second”, etc. are usedonly for the purpose of distinguishing one component from anothercomponent, and are not limited by ordinal numbers.

For instance, a first component may be referred to as a secondcomponent, or similarly, the second component may be referred to as thefirst component, without departing from the scope of the presentinvention.

According to one embodiment of the present disclosure, a polyamide-imideresin film can be provided, including: a polyamide-imide block copolymercontaining an amide repeating unit to which an isophthaloyl group and anaromatic diamine residue are bonded; an imide repeating unit; and atrivalent functional group containing an aromatic tricarbonyl group,wherein retardation (Rth) in the thickness direction measured at awavelength of 590 nm is 2000 nm or less.

As a result of studies by the present inventors, it has been foundthrough experiments that when a polyamide-imide block copolymercontaining an amide repeating unit to which an isophthaloyl group and anaromatic diamine residue are bonded, an imide repeating unit, and atrivalent functional group containing an aromatic tricarbonyl group isused, it is possible to provide a polyamide-imide resin film which iscolorless and transparent and has excellent mechanical properties and alow birefringence index, thereby completing the present invention.

Specifically, as the polyamide-imide block copolymer contains an amiderepeating unit to which an isophthaloyl group and an aromatic diamineresidue are bonded, it can have a polymer inner structure capable of notonly preventing chain packing by including a repeating unit having abent structure in the main chain, thus reducing charge transfer betweenaromatic groups (benzene, etc.), but also slightly reducing the chainorientation to decrease the directionality, whereby it is possible toprovide a film which is excellent in processability and thus facilitatesformation of films, and which is colorless and transparent and hasexcellent mechanical properties.

In addition, as the polyamide-imide block copolymer includes a trivalentfunctional group containing an aromatic tricarbonyl group, it canprovide a predetermined crosslinking structure or a network structuretherein. By the block copolymerization of the repeating units containingit, a rigid and stable network structure can be formed in the copolymer,and such a rigid and stable network structure allows the polyamide-imideblock copolymer to exhibit improved mechanical properties while beingcolorless and transparent.

More specifically, in the polyamide-imide block copolymer, a blockcontaining the amide repeating unit and a block containing the imiderepeating unit may be bonded via a trivalent functional group containingthe aromatic tricarbonyl group.

The thickness of the polyamide-imide resin film is not particularlylimited, but the polyamide-imide resin film may have a thickness of 5 μmto 100 μm in consideration of optical characteristics, mechanicalproperties, birefringence, and the like of the film.

Further, the retardation (Rth) in the thickness direction measured at awavelength of 590 nm with respect to the polyamide-imide resin film maybe 2000 nm or less, 200 nm to 2000 nm, 300 no to 1500 nm, 400 no to 1200nm, or 500 no to 1000 nm.

The polyamide-imide resin film may have isotropy.

As the polyamide-imide resin film has retardation (Rth) in the thicknessdirection measured at a wavelength of 590 nm of 2000 nm or less, it hasisotropy and thus has a certain transparency in all directions inoptical characteristics, and can have a feature that the reproducibilityaccording to the manufacturing conditions and the thickness is superiorto that of anisotropic materials at the time of producing the film.

The thickness-direction retardation (Rth) of the polyamide-imide resinfilm can be confirmed by a commonly known measurement method andmeasurement apparatus.

For example, the retardation (Rth) in the thickness direction can bedetermined using a measuring apparatus manufactured by AXOMETRICS, Inc.under the trade name of AxoScan, Prism Coupler, and the like.

In addition, the retardation (Rth) in the thickness direction can bedetermined by: inputting a value of a refractive index (589 nm) of thepolyamide-imide resin film into the measuring apparatus, then measuringthe thickness-direction retardation of the polyamide-imide resin film byusing light at a wavelength of 590 nm under conditions of a temperatureof 25° C. and a humidity of 40%, and converting the measured value ofthe thickness-direction retardation thus determined (the value ismeasured according to the automatic measurement (automatic calculation)of the measuring apparatus) into a retardation value per 10 μm of thethickness of the film.

In addition, the size of the polyimide film as the measurement sample isnot particularly limited, as long as it is larger than a lightmeasurement unit (diameter: about 1 cm) of a stage of the measuringapparatus. However, the size may be a length of 76 mm, a width of 52 mm,and a thickness of 13 μm.

The value of the “refractive index (589 nm) of the polyimide film”utilized in the measurement of the thickness-direction retardation (Rth)can be determined by forming an unstretched film including the same kindof polyamide-imide resin film as the polyamide-imide resin film forforming the film to be measured for the retardation, and then measuringthe unstretched film as a measurement sample (in the case where the filmto be measured is an unstretched film, the film can be directly used asthe measurement sample) for the refractive index for light at 589 nm inan in-plane direction (the direction perpendicular to the thicknessdirection) of the measurement sample by using a refractiveindex-measuring apparatus (manufactured by Atago Co., Ltd. under thetrade name of “NAR-1T SOLID”) as a measuring apparatus under a lightsource of 589 nm and a temperature condition of 23° C.

Further, when the measurement sample is unstretched, the refractiveindex in the in-plane direction of the film is the same in any directionin the plane, and measuring this refractive index makes it possible tomeasure the intrinsic refractive index of the polyamide-imide resin film(further, since the measurement sample is unstretched, Nx=Ny issatisfied, where Nx is a refractive index in a direction of a slow axisin the plane, and Ny is a refractive index in an in-plane directionperpendicular to the direction of the slow axis).

In this way, an unstretched film is utilized to measure the intrinsicrefractive index (589 nm) of the polyamide-imide resin film, and themeasurement value thus obtained is utilized in the measurement of theabove-described thickness-direction retardation (Rth).

Here, the size of the polyamide-imide resin film as a measurement sampleis not particularly limited, as long as the size can be utilized in therefractive index-measuring apparatus. The size may be 1 cm square (1 cmin length and width) and 13 μm in thickness.

On the other hand, the polyamide-imide block copolymer may include afirst repeating unit represented by the following Chemical Formula 1,and a second repeating unit represented by the following ChemicalFormula 2, and optionally, it may further include a third repeating unitrepresented by the following Chemical Formula 3.

In Chemical Formula 1,

-   -   each R¹¹ is the same as or different from each other in each        repeating unit, and each independently represents a single bond,        —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)—        (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—,        —C(CF₃)₂—, —C(═O)NH—, or a divalent aromatic organic group        having 6 to 30 carbon atoms;    -   each R¹² independently represents —H, —F, —Cl, —Br, —I, —CF₃,        —CCI₃, —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂O₂H₅, a silyl group        having three aliphatic organic groups having 1 to 10 carbon        atoms, an aliphatic organic group having 1 to 10 carbon atoms,        or an aromatic organic group having 6 to 20 carbon atoms;    -   n1 and ml are each independently an integer of 0 to 3;    -   each Y¹⁰ is the same as or different from each other in each        repeating unit, and each independently includes a divalent        aromatic organic group having 6 to 30 carbon atoms, wherein the        aromatic organic group exists alone, two or more aromatic        organic groups are bonded to each other to form a divalent        condensed ring, or two or more of the aromatic organic groups        are linked by a single bond, a fluorenyl group, —O—, —S—,        —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein        1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or        —C(═O)NH—;    -   E¹¹, E¹², and E¹³ are each independently a single bond or —NH—;        and    -   each Z¹⁰ is the same as or different from each other in each        repeating unit, and each represents a trivalent linking group        derived from one or more compounds selected from the group        consisting of triacyl halide, tricarboxylic acid, and        tricarboxylate.

*E²¹-Y²⁰-E²²-Z²⁰-E²³*  [Chemical Formula 2]

*E³¹-Y³⁰-E³²-Z³⁰-E³³*  [Chemical Formula 2]

In Chemical Formulae 2 and 3,

-   -   Y²⁰ and Y³⁰ are the same as or different from each other in each        repeating unit, and each independently includes a divalent        aromatic organic group having 6 to 30 carbon atoms, wherein the        aromatic organic group exists alone, two or more of the aromatic        organic groups are bonded to each other to form a divalent        condensed ring, or two or more of the aromatic organic groups        are linked by a single bond, a fluorenyl group, —O—, —S—,        —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein        1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or        —C(═O)NH—;    -   E²¹, E², E²³, E³¹, E³², and E³³ are each independently a single        bond or —NH—;    -   Z²⁰ and Z³⁰ are the same as or different from each other in each        repeating unit, and each is a divalent linking group in the form        of —C(═O)-A-C(═O)— derived from one or more compounds selected        from the group consisting of diacyl halide, dicarboxylic acid,        and dicarboxylate;    -   in Z²⁰ and Z³⁰, A is a divalent aromatic organic group having 6        to 20 carbon atoms, a divalent heteroaromatic organic group        having 4 to 20 carbon atoms, a divalent alicyclic organic group        having 6 to 20 carbon atoms, or a divalent organic group in        which two or more of the organic groups are linked by a single        bond, a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—,        —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein        1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—;    -   in Z²⁰, two carbonyl groups connected to both sides of A are        bonded to each other at a meta position with respect to A; and    -   in Z³⁰, two carbonyl groups connected to both sides of A are        bonded at a para position to each other with respect to A.

The polyamide-imide block copolymer may have a structure in which adivalent linking group in the form of —C(═O)-A-C(═O)— is introduced intoZ²⁰ of the second repeating unit and Z³⁰ of the third repeating unit,respectively.

In particular, the polyamide-imide block copolymer has both a structurein which two carbonyl groups connected to both sides of A in Z²⁰ arebonded to a meta position with respect to A, and a structure in whichtwo carbonyl groups connected to both sides of A in Z³⁰ are bonded tothe para position with respect to A.

Accordingly, the polyamide-imide block copolymer exhibits excellentprocessability resulting from bonding at a meta position of the secondrepeating unit, and at the same time, exhibits excellent mechanicalproperties (in particular, hardness and modulus) resulting from bondingat a para position of the third repeating unit.

That is, the polyamide-imide block copolymer may include a firstrepeating unit having an introduced trivalent brancher (Z¹⁰), a secondrepeating unit having an introduced group (Z²⁰) in which two carbonylgroups are bonded to the meta position, and a third repeating unithaving an introduced group (Z³⁰) in which two carbonyl groups are bondedto the para position.

Consequently, the polyamide-imide block copolymer is excellent inprocessability of the resin itself, and therefore, it not onlyfacilitates formation of films using it, but also enables provision of afilm having improved mechanical properties while being colorless andtransparent.

Hereinafter, each repeating unit contained in the polyamide-imide blockcopolymer will be described.

(I) First Repeating Unit

The polyamide-imide block copolymer includes the first repeating unitrepresented by Chemical Formula 1.

In Chemical Formula 1, each R¹¹ is the same as or different from eachother in each repeating unit, and each independently represents a singlebond, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)—(wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—,—C(═O)NH—, or a divalent aromatic organic group having 6 to 30 carbonatoms.

Here, the single bond means a case where R¹¹ in Chemical Formula 1 is achemical bond that simply connects groups on both sides.

The divalent aromatic organic group having 6 to 30 carbon atoms existsalone; two or more aromatic organic groups are bonded to each other toform a divalent condensed ring; or it is a divalent organic group inwhich two or more aromatic organic groups are linked by a single bond, afluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—,—(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—,—C(CF₃)₂—, or —C(═O)NH—.

Specifically, each R¹¹ is the same as or different from each other ineach repeating unit, and may each independently represent a single bond,—O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, —C(═O)NH—.More specifically, R¹¹ may be a single bond or —C(CF₃)₂—.

In Chemical Formula 1, each R¹² independently represents —H, —F, —Cl,—Br, —I, —CF₃, —CCl₃, —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silylgroup having three aliphatic organic groups having 1 to 10 carbon atoms,an aliphatic organic group having 1 to 10 carbon atoms, or an aromaticorganic group having 6 to 20 carbon atoms.

In Chemical Formula 1, the n1 and ml are each independently an integerof 0 to 3. Preferably, the n1 and ml are each independently an integerof 0 to 1.

In Chemical Formula 1, each Y¹⁰ is the same as or different from eachother in each repeating unit, and each independently includes a divalentaromatic organic group having 6 to 30 carbon atoms.

Here, the divalent aromatic organic group exists alone; two or morearomatic organic groups are bonded to each other to form a condensedring; or two or more aromatic organic groups may be linked by a singlebond, a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—,—Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10),—C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—.

Specifically, Y¹⁰ may be a divalent organic group represented by thefollowing structural formula:

-   -   wherein, in the above structural formula,    -   R^(a) is a single bond, a fluorenyl group, —O—, —S—, —C(═O)—,        —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10),        —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or        —C(═O)NH—;    -   each R^(b) is independently —H, —F, —Cl, —Br, —I, —CF₃, —CCl₃,        —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silyl group having        three aliphatic organic groups having 1 to 10 carbon atoms, an        aliphatic organic group having 1 to 10 carbon atoms, or an        aromatic organic group having 6 to 20 carbon atoms; and p and q        are each independently an integer of 1 to 4.

In Chemical Formula 1, E¹¹, E¹², and E¹³ are each independently a singlebond or —NH—. Here, the single bond means a case where E¹¹, E¹², and E¹³simply connect groups on both sides or repeating units.

In Chemical Formula 1, Z¹⁰ is a brancher having three reactivesubstituents, which are the same as or different from each other in eachrepeating unit, and each represents a trivalent linking group derivedfrom one or more compounds selected from the group consisting of triacylhalide, tricarboxylic acid, and tricarboxylate.

Specifically, Z¹⁰ may be a trivalent linking group derived from one ormore compounds which are selected from the group consisting of anaromatic triacyl halide having 6 to 20 carbon atoms, an aromatictricarboxylic acid having 6 to 20 carbon atoms, an aromatictricarboxylate having 6 to 20 carbon atoms, an N-containingheteroaromatic triacyl halide having 4 to 20 carbon atoms, anN-containing heteroaromatic tricarboxylic acid having 4 to 20 carbonatoms, an N-containing heteroaromatic tricarboxylate having 4 to 20carbon atom, an alicyclic triacyl halide having 6 to 20 carbon atoms, analicyclic tricarboxylic acid having 6 to 20 carbon atoms, and analicyclic tricarboxylate having 6 to 20 carbon atoms.

More specifically, Z¹⁰ may be a group selected from the grouprepresented by the following structural Formulae:

For example, Z¹⁰ may be a trivalent linking group derived from one ormore compounds which are selected from the group consisting of1,3,5-benzenetricarbonyl trichloride, 1,2,4-benzenetricarbonyltrichloride, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylicacid, trimethyl 1,3,5-benzenetricarboxylate, and trimethyl1,2,4-benzenetricarboxylate.

More specifically, the first repeating unit may include a repeating unitrepresented by the following Chemical Formula 1-a:

-   -   wherein, in Chemical Formula 1-a,    -   each R¹¹ is the same as or different from each other in each        repeating unit, and each independently represents a single bond,        —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)—        (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—,        —C(CF₃)₂—, —C(═O)NH—, or a divalent aromatic organic group        having 6 to 30 carbon atoms;    -   R¹² and R¹⁴ each independently represent —H, —F, —Cl, —Br, —I,        —CF₃, —CCl₃, —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —C₂C₂H₅, a silyl        group having three aliphatic organic groups having 1 to 10        carbon atoms, an aliphatic organic group having 1 to 10 carbon        atoms, or an aromatic organic group having 6 to 20 carbon atoms;    -   each R¹³ is the same as or different from each other in each        repeating unit, and each independently represents a single bond,        a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—,        —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein        1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—;    -   n1 and ml are each independently an integer of 0 to 3;    -   n2 and m2 are each independently an integer of 1 to 4;    -   E¹¹, E¹², and E¹³ are each independently a single bond or —NH—;        and    -   each Z¹⁰ is the same as or different from each other in each        repeating unit, and each represents a trivalent linking group        derived from one or more compounds selected from the group        consisting of triacyl halide, tricarboxylic acid, and        tricarboxylate.

Further, in Chemical Formula 1-a,

-   -   R¹¹ and R¹³ are the same as or different from each other in each        repeating unit, and each independently represent a single bond        or —C(CF₃)₂—; and    -   Z¹⁰ may be a trivalent linking group derived from one or more        compounds which are selected from the group consisting of        1,3,5-benzenetricarbonyl trichloride, 1,2,4-benzenetricarbonyl        trichloride, 1,3,5-benzenetricarboxylic acid,        1,2,4-benzenetricarboxylic acid, trimethyl        1,3,5-benzenetricarboxylate, and trimethyl        1,2,4-benzenetricarboxylate.

Preferably, the first repeating unit may include a repeating unitrepresented by the following Chemical Formulae 1-b and 1-c:

-   -   wherein, in Chemical Formulae 1-b and 1-c,    -   R¹² and R¹⁴ independently represent —H, —F, —Cl, —Br, —I, —CF₃,        —CCl₃, —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silyl group        having three aliphatic organic groups having 1 to 10 carbon        atoms, an aliphatic organic group having 1 to 10 carbon atoms,        or an aromatic organic group having 6 to 20 carbon atoms;    -   n1 and ml are each independently an integer of 0 to 3; and    -   n2 and m2 are each independently an integer of 1 to 4.

(ii) Second Repeating Unit

*E²¹-Y²⁰-E²²-Z²⁰-E²³-*  [Chemical Formula 2]

The polyamide-imide block copolymer includes the second repeating unitrepresented by Chemical Formula 2.

In Chemical Formula 2, each Y²⁰ is the same as or different from eachother in each repeating unit, and each independently includes a divalentaromatic organic group having 6 to 30 carbon atoms.

Here, the divalent aromatic organic group exists alone; two or morearomatic organic groups are bonded to each other to form a divalentcondensed ring; or two or more aromatic organic groups may be linked bya single bond, a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—,—Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10),—C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—.

Preferably, Y²⁰ may be a divalent organic group represented by thefollowing structural formula:

In the above structural formula,

-   -   R^(a′) is a single bond, a fluorenyl group, —O—, —S—, —C(═O)—,        —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10),        —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or        —C(═O)NH—;    -   each R^(b′) is independently —H, —F, —Cl, —Br, —I, —CF₃, —CCl₃,        —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silyl group having        three aliphatic organic groups having 1 to 10 carbon atoms, an        aliphatic organic group having 1 to 10 carbon atoms, or an        aromatic organic group having 6 to 20 carbon atoms; and    -   p′ and q′ are each independently an integer of 1 to 4.

In Chemical Formula 2, E²¹, E²², and E² are each independently a singlebond or —NH—. Here, the single bond means a case where E²¹, E²², and E²³simply connect groups on both sides or repeating units.

In Chemical Formula 2, each Z²⁰ is the same as or different from eachother in each repeating unit, and each is a divalent linking group inthe form of —C(═O)-A-C(═O)— derived from one or more compounds which areselected from the group consisting of diacyl halide, dicarboxylic acid,and dicarboxylate.

A is a divalent aromatic organic group having 6 to 20 carbon atoms, or adivalent heteroaromatic organic group having 4 to 20 carbon atoms, adivalent alicyclic organic group having 6 to 20 carbon atoms, or adivalent organic group in which two or more of the organic groups arelinked by a single bond, a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—,—S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—.

In particular, in Z²⁰, two carbonyl groups connected to both sides of Aare bonded at a meta position to each other with respect to A.

Specifically, Z²⁰ may be a group selected from the group consisting ofthe following structural Formulae:

-   -   wherein, in the above structural Formulae,    -   R²¹ is —H, —F, —Cl, —Br, —I, a silyl group having three        aliphatic organic groups having 1 to 10 carbon atoms, an        aliphatic organic group having 1 to 10 carbon atoms, or an        aromatic organic group having 6 to 20 carbon atoms,    -   a1 is an integer of 0 to 3, and    -   a2 is an integer of 0 to 2.

More specifically, Z²⁰ may be a group selected from the grouprepresented by the following structural Formulae:

For example, Z²⁰ may be a divalent linking group derived from one ormore compounds which are selected from isophthaloyl dichloride (IPC),isophthalic acid, cyclohexane-1,3-dicarbonyl chloride,cyclohexane-1,3-dicarboxylic acid, pyridine-3,5-dicarbonyl chloride,pyridine-3,5-dicarboxylic acid, pyrimidine-2,6-dicarbonyl chloride), andpyrimidine-2,6-dicarboxylic acid.

Preferably, the second repeating unit may include a repeating grouprepresented by the following Chemical Formula 2-a:

-   -   wherein, in Chemical Formula 2-a,    -   each R²² is the same as or different from each other in each        repeating unit, and each independently represents a single bond,        a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—,        —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein        1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—;    -   each R²³ independently represents —H, —F, —Cl, —Br, —I, —CF₃,        —CCI₃, —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silyl group        having three aliphatic organic groups having 1 to 10 carbon        atoms, an aliphatic organic group having 1 to 10 carbon atoms,        or an aromatic organic group having 6 to 20 carbon atoms;    -   n3 and m3 are each independently an integer of 1 to 4;    -   E²¹, E², and E³ are each independently a single bond or —NH—;        and    -   Z²⁰ is a group selected from the group represented by the        following structural Formulae:

More preferably, the second repeating unit may include a repeating grouprepresented by the following Chemical Formula 2-b:

-   -   wherein, in Chemical Formula 2-b,    -   each R²³ is independently —H, —F, —Cl, —Br, —I, —CF₃, —CCl₃,        —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silyl group having        three aliphatic organic groups having 1 to 10 carbon atoms, an        aliphatic organic group having 1 to 10 carbon atoms, or an        aromatic organic group having 6 to 20 carbon atoms; and    -   n3 and m3 are each independently an integer of 1 to 4.

(iii) Third Repeating Unit

*+E³¹-Y³⁰-E³²-Z³⁰-E³³*  [Chemical Formula 3]

The polyamide-imide block copolymer includes the third repeating unitrepresented by Chemical Formula 3 together with the second repeatingunit represented by Chemical Formula 2.

In Chemical Formula 3, each Y³⁰ is the same as or different from eachother in each repeating unit, and each independently includes a divalentaromatic organic group having 6 to 30 carbon atoms.

Here, the divalent aromatic organic group exists alone; two or morearomatic organic groups are bonded to each other to form a divalentcondensed ring; or two or more aromatic organic groups may be linked bya single bond, a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—,—Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10),—C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—.

Preferably, Y³⁰ may be a divalent organic group represented by thefollowing structural formula:

-   -   wherein, in the above structural formula,    -   R^(a″) is a single bond, a fluorenyl group, —O—, —S—, —C(═O)—,        —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10),        —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or        —C(═O)NH—;    -   each R^(b″) is independently —H, —F, —Cl, —Br, —I, —CF₃, —CCl₃,        —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂O₂H₅, a silyl group having        three aliphatic organic groups having 1 to 10 carbon atoms, an        aliphatic organic group having 1 to 10 carbon atoms, or an        aromatic organic group having 6 to 20 carbon atoms; and    -   p″ and q″ are each independently an integer of 1 to 4.

In Chemical Formula 3, E³¹, E³², and E³³ are each independently a singlebond or —NH—. Here, the single bond means a case where E³¹, E³², and E³³simply connect groups on both sides or repeating units.

In Chemical Formula 3, each Z³⁰ is the same as or different from eachother in each repeating unit, and each is a divalent linking group inthe form of —C(═O)-A-C(═O)— derived from one or more compounds which areselected from the group consisting of diacyl halide, dicarboxylic acid,and dicarboxylate.

A is a divalent aromatic organic group having 6 to 20 carbon atoms, adivalent heteroaromatic organic group having 4 to 20 carbon atoms, adivalent alicyclic organic group having 6 to 20 carbon atoms, or adivalent organic group in which two or more of the organic groups arelinked by a single bond, a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—,—S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—.

In particular, in Z³⁰, two carbonyl groups connected to both sides of Aare bonded at a para position to each other with respect to A.

Specifically, Z³⁰ may be a group selected from the group consisting ofthe following structural Formulae:

wherein, in the above structural Formulae,

-   -   R³¹ and R³² are each independently —H, —F, —Cl, —Br, —I, a silyl        group having three aliphatic organic groups having 1 to 10        carbon atoms, an aliphatic organic group having 1 to 10 carbon        atoms, or an aromatic organic group having 6 to 20 carbon atoms;    -   b1 and b2 are each independently an integer of 0 to 3; and    -   b3 is an integer of 0 to 2.

More specifically, Z³⁰ may be a group selected from the followingstructural Formulae:

For example, Z³⁰ may be a divalent linking group derived from one ormore compounds which are selected from the group consisting ofterephthaloyl chloride (TPC), terephthalic acid,cyclohexane-1,4-dicarbonyl chloride, cyclohexane-1,4-dicarboxylic acid,pyridine-2,5-dicarbonyl chloride, pyridine-2,5-dicarboxylic acid,pyrimidine-2,5-dicarbonyl chloride, pyrimidine-2,5-dicarboxylic acid,4,4′-biphenyldicarbonyl chloride (BPC), and 4,4′-biphenyldicarboxylicacid.

Preferably, the third repeating unit may include a repeating unitrepresented by the following Chemical Formula 3-a:

-   -   wherein, in Chemical Formula 3-a,    -   each R³³ is the same as or different from each other in each        repeating unit, and each independently represents a single bond,        a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—,        —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein        1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂— or —C(═O)NH—;    -   each R³⁴ is independently —H, —F, —Cl, —Br, —I, —CF₃, —CCl₃,        —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silyl group having        three aliphatic organic groups having 1 to 10 carbon atoms, an        aliphatic organic group having 1 to 10 carbon atoms, or an        aromatic organic group having 6 to 20 carbon atoms;    -   n4 and m4 are each independently an integer of 1 to 4;    -   E³¹, E³², and E³³ are each independently a single bond or —NH—;        and    -   Z³⁰ is a group selected from the group represented by the        following structural Formulae:

More preferably, the third repeating unit may include a repeating unitrepresented by the following Chemical Formulae 3-b or 3-c:

-   -   wherein, in Chemical Formulae 3-b and 3-c,    -   each R³⁴ is independently —H, —F, —Cl, —Br, —I, —CF₃, —CCl₃,        —CBr₃, —Cl₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silyl group having        three aliphatic organic groups having 1 to 10 carbon atoms, an        aliphatic organic group having 1 to 10 carbon atoms, or an        aromatic organic group having 6 to 20 carbon atoms; and    -   n4 and m4 are each independently an integer of 1 to 4.

According to an embodiment of the invention, the presence of the secondrepeating unit represented by Chemical Formula 2 and the third repeatingunit represented by Chemical Formula 3 in the polyamide-imide blockcopolymer can be confirmed by NMR spectroscopy.

For example, the polyamide-imide block copolymer may show ¹H NMRspectrum (300 MHz, DMSO-d6, standard TMS) having at least one peakwithin a δ range of 10.80 ppm or more and 11.00 ppm or less, and atleast one peak within a δ range of 10.60 ppm or more and 10.80 ppm orless.

That is, in the ¹H NMR spectrum of the polyamide-imide block copolymer,the peak according to Z²⁰ (including two carbonyl groups bonded to ameta position) of the second repeating unit may be observed within the 6range of 10.80 ppm or more and 11.00 ppm or less; and the peak accordingto Z³⁰ (including two carbonyl groups bonded to a para position) of thethird repeating unit may be observed within the δ range of 10.60 ppm ormore and 10.80 ppm or less.

In the polyamide-imide block copolymer, the molar ratio of the thirdrepeating unit to the second repeating unit may be 0.5 to 3.

The polyamide-imide block copolymer containing the first repeating unit,the second repeating unit and the third repeating unit at theabove-mentioned molar ratio at the same time can be expected to have aneffect of improving transparency of the film mainly attributable to thefirst repeating unit having an introduced brancher (Z¹), an effect ofimproving the processability of the film mainly attributable to thesecond repeating unit having an introduced Z² in which two —C(═O)— arelocated at a meta position, and an effect of improving the mechanicalproperties (hardness and modulus) mainly attributable to the thirdrepeating unit having an introduced Z³ in which two —C(═O)— are locatedat a para position.

Further, the polyamide-imide block copolymer has a rigid and stablenetwork structure, and thus can have a higher molecular weight than ageneral linear polyimide resin.

Specifically, the polyamide-imide block copolymer has a weight averagemolecular weight of 100,000 to 5,000,000 g/mol, preferably 200,000 to1,000,000 g/mol, more preferably 300,000 to 750,000 g/mol, and even morepreferably 500,000 to 650,000 g/mol.

In addition, the polyamide-imide block copolymer may exhibit ayellowness index (Y.I.) of 3.0 or less, 2.90 or less, 2.80 or less, 2.70or less, 2.60 or less, or 2.55 or less as measured for a specimen havinga thickness of 30±2 Cm according to ASTM D1925.

The polyamide-imide resin film can be used as material for variousmolded articles requiring high mechanical properties together withcolorless transparency.

For example, the polyimide-based film containing the polyamide-imideblock copolymer may be applied to substrates for displays, protectivefilms for displays, touch panels, cover films for flexible or foldabledevices, and the like.

Meanwhile, the polyimide-based film can be produced by a conventionalmethod such as a dry method or a wet method using the polyamide-imideblock copolymer. For example, the polyimide-based film may be obtainedby coating a solution containing the copolymer on an arbitrary supportto form a film, and then evaporating the solvent from the film to dryit.

If necessary, stretching and heat treating the polyimide-based film maybe carried out.

As the polyimide-based film is produced using the polyamide-imide blockcopolymer, it can exhibit excellent mechanical properties while beingcolorless and transparent.

Specifically, the polyimide-based film may exhibit a pencil hardness ofan HB grade or higher as measured according to ASTM D3363.

In addition, the polyamide-imide block copolymer may exhibit ayellowness index (Y.I.) of 3.0 or less, 2.90 or less, 2.80 or less, 2.70or less, 2.60 or less, or 2.55 or less as measured for a specimen havinga thickness of 50±2 μm according to ASTM D1925.

Advantageous Effects

According to the present invention, a polyamide-imide resin film havingexcellent mechanical properties while being colorless and transparentcan be provided. Such a polyamide-imide resin film can be applied tosubstrates for displays, protective films for displays, touch panels,and cover films for flexible or foldable devices due to theabove-described properties.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, preferred examples are presented to facilitateunderstanding of the present invention. However, the following examplesare given for illustrative purposes only, and the scope of the presentinvention is not intended to be limited to or by these examples.

Example 1

3.203 g (1.01 eq., 0.0101 mol) of 2,2′-bis(trifluoromethyl)benzidine;4.3647 g (0.9825 eq., 0.009825 mol) of4,4′-(hexafluoroisopropylidene)diphthalic anhydride; 0.0133 g (0.005eq., 0.00005 mol) of 1,3,5-benzenetricarbonyl trichloride; and 73 ml ofN,N-dimethylacetamide were placed in a 250 mL round flask equipped witha Dean-Stark apparatus and a condenser, and the mixture was stirred at0° C. under a nitrogen atmosphere to carry out a polymerizationreaction.

After 4 hours, to the product of the polymerization reaction, 9.575 g(2.99 eq., 0.0299 mol) of 2,2′-bis(trifluoromethyl)benzidine; 6.1109 g(3.01 eq., 0.0301 mol) of isophthaloyl dichloride; and 66 ml ofN,N-dimethylacetamide were added, and the mixture was stirred at roomtemperature under a nitrogen atmosphere and subjected to apolymerization reaction for 4 hours.

To the polyamic acid solution obtained by the polymerization reaction,14 ml of acetic anhydride and 12 ml of pyridine were added, and themixture was stirred in an oil bath at a temperature of 40° C. for 15hours to carry out a chemical imidization reaction.

After completion of the reaction, the solid content was precipitatedusing water and ethanol, and the precipitated solid component wasfiltered and then dried under vacuum at 100° C. for 6 hours or more toobtain a polyamide-imide block copolymer having the following repeatingunits (weight average molecular weight of 500,000 g/mol).

Comparative Example 1

4.851 g (1.01 eq., 0.01515 mol) of 2,2′-bis(trifluoromethyl)benzidine;6.546 g (0.9825 eq., 0.01474 mol) of4,4′-(hexafluoroisopropylidene)diphthalic anhydride; 0.0199 g (0.005eq., 0.000075 mol) of 1,3,5-benzenetricarbonyl trichloride; and 58 ml ofN,N-dimethylacetamide were placed in a 250 mL round flask equipped witha Dean-Stark apparatus and a condenser, and the mixture was stirred at0° C. under a nitrogen atmosphere to carry out a polymerizationreaction.

After 4 hours, to the product of the polymerization reaction, 4.755 g(0.99 eq., 0.01485 mol) of 2,2-bis(trifluoromethyl)benzidine; 3.075 g(1.01 eq., 0.0101 mol) of terephthaloyl chloride; and 120 ml ofN,N-dimethylacetamide were added, and the mixture was stirred at roomtemperature under a nitrogen atmosphere and subjected to apolymerization reaction for 4 hours.

To the polyamic acid solution obtained by the polymerization reaction,14 ml of acetic anhydride and 12 ml of pyridine were added, and themixture was stirred in an oil bath at a temperature of 40° C. for 15hours to carry out a chemical imidization reaction.

After completion of the reaction, the solid content was precipitatedusing water and ethanol, and the precipitated solid component wasfiltered and then dried at 100° C. under vacuum for 6 hours or more toobtain a polyamide-imide block copolymer having the following repeatingunits (weight average molecular weight of 300,000 g/mol).

Example 2

The copolymer obtained in Example 1 was dissolved inN,N-dimethylacetamide to prepare an about 10% (w/v) polymer solution.The polymer solution was poured on a glass plate heated to 40° C., andthe polymer solution was cast to a thickness of 1200 μm using a filmapplicator and dried for 60 minutes.

The mixture was slowly heated from 120° C. to 200° C. for 4 hours undera nitrogen purge (maintained at 200° C. for 120 minutes), and thengradually cooled to obtain a film having a thickness of 30±2 In that waspeeled off from the glass substrate.

Apart from this, a film having a thickness of 50±2 μm was obtained bythe above-described method using the polymer solution.

Comparative Example 2

A film having a thickness of 30±2 μm and a film having a thickness of50±2 μm were respectively obtained in the same manner as in Example 2,except that the copolymer obtained in Comparative Example 1 was usedinstead of the copolymer obtained in Example 1.

Test Example

The following characteristics were evaluated for the films obtained inthe examples and comparative examples, and the results are shown inTable 1 below.

(1) Pencil Hardness

The pencil hardness of a film having a thickness of 30±2 μm was measuredin accordance with the ASTM D3363 method (750 gf) using a PencilHardness Tester.

Specifically, various hardnesses of pencils were fixed to the tester andpassed on the film, and then the decree of occurrence of scratches onthe film was observed with the naked eye or with a microscope. When morethan 70% of the total passes did not produce scratches, a valuecorresponding to the hardness of the pencil was evaluated as the pencilhardness of the film.

(2) Mechanical Properties

The elastic modulus (EM, GPa), the ultimate tensile strength (TS, MPa),and the tensile elongation (TE, %) of the films having a thickness of30±2 μm were measured in accordance with the ASTM D882 method using auniversal testing machine.

(3) Yellowness Index (Y.I.)

The yellowness index of the films having a thickness of 30±2 n m wasmeasured in accordance with the ASTM D1925 method using a UV-2600 UV-VisSpectrometer (SHIMADZU).

(4) Haziness

The haziness of the films having a thickness of 30±2 Inn was measured inaccordance with the ASTM D1003 method using a COH-400 Spectrophotometer(NIPPON DENSHOKU INDUSTRIES).

(5) Folding Endurance

The folding endurance of the films was evaluated using an MIT type offolding endurance tester. Specifically, a specimen (1 cm*7 cm) of thefilm was loaded into the folding endurance tester, and folded to anangle of 135° at a rate of 175 rpm on the left and right sides of thespecimen, with a radius of curvature of 0.8 mm and a load of 250 g,until the specimen was bent and fractured. The number of reciprocatingbending cycles was measured as the folding endurance.

(6) Processablility

The degree of transparency of the film having a thickness of 50±2 μm ascompared with the film having a thickness of 30±2 μm was observed withthe naked eye.

When the transparency indicated by the film having a thickness of 50±2μm was equal to that of the film having a thickness of 30±2 μm, the filmwas evaluated as having good processability (“0”), and when thetransparency was degraded (for example, was opaque), the film wasevaluated as having bad processability (“X”).

(7) Retardation (Rth) in Thickness Direction

The retardation (Rth) in the thickness direction was determined bydirectly using the polymer film (length: 76 mm, width: 52 mm, andthickness: 13 μm) prepared in each of the examples and comparativeexamples as a measuring sample, using a measuring apparatus manufacturedby AXOMETRICS, Inc. under the trade name of AxoScan, inputting a valueof a refractive index (the refractive index at a wavelength of 589 nm ofthe film obtained by the measurement of the refractive index describedabove) of each polymer film into the measuring apparatus, measuring thethickness-direction retardation by using light at a wavelength of 590 nmunder conditions of a temperature of 25° C. and a humidity of 40%; andthen converting the measured value of the thickness-directionretardation thus obtained (the value was measured according to theautomatic measurement of the measuring apparatus) into a retardationvalue per 10 μm of the thickness of the film.

TABLE 1 Film Example 2 Comparative Example 2 Copolymer Example 1Comparative Example 1 Rth 853 3138 Pencil hardness F F (H) Elasticmodulus (GPa) 2.41 3.48 Tensile elongation (%) 16.8 7.7 Yellowness Index1.77 2.22 Haze 0.7 1.14 Processability ◯ X

Referring to Table 1 above, it was confirmed that the polyamide-imideresin film of Example 2 had low yellowness index and haze and thus hadcolorless and transparent optical characteristics, and further exhibiteda low level of elastic modulus, high tensile elongation, and the liketogether with high pencil hardness, thus having excellent mechanicalproperties.

On the other hand, it was confirmed that the polymer film of ComparativeExample 2 had a high yellowness index and haze value, and thus had ahigher elastic modulus and lower tensile elongation while being closerto a colored film, as compared with that of the film of Example 2, thushaving bad processability.

1. A polyamide-imide resin film comprising: a polyamide-imide blockcopolymer containing an amide repeating unit having an isophthaloylgroup and an aromatic diamine residue; an imide repeating unit; and atrivalent functional group containing an aromatic tricarbonyl group,wherein retardation (Rth) in the thickness direction measured at awavelength of 590 nm is 2000 nm or less.
 2. The polyamide-imide resinfilm according to claim 1, wherein a block containing the amiderepeating unit and a block containing the imide repeating unit arebonded via the trivalent functional group containing the aromatictricarbonyl group.
 3. The polyamide-imide resin film according to claim1, wherein the polyamide-imide resin film has isotropy.
 4. Thepolyamide-imide resin film according to claim 1, wherein thepolyamide-imide resin film has a thickness of 5 μm to 100 μm.
 5. Thepolyamide-imide resin film according to claim 1, wherein thepolyamide-imide block copolymer includes a first repeating unitrepresented by Chemical Formula 1 and a second repeating unitrepresented by Chemical Formula 2:

wherein, in the Chemical Formula 1, each R¹¹ is the same as or differentfrom each other in each repeating unit, and each independentlyrepresents a single bond, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—,—Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10),—C(CH₃)₂—, —C(CF₃)₂—, —C(═O)NH—, or a divalent aromatic organic grouphaving 6 to 30 carbon atoms; each R¹² independently represents —H, —F,—Cl, —Br, —I, —CF₃, —CCl₃, —CBr₃, —CI₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, asilyl group having three aliphatic organic groups having 1 to 10 carbonatoms, an aliphatic organic group having 1 to 10 carbon atoms, or anaromatic organic group having 6 to 20 carbon atoms; n1 and ml are eachindependently an integer of 0 to 3; each Y¹⁰ is the same as or differentfrom each other in each repeating unit, and each independently includesa divalent aromatic organic group having 6 to 30 carbon atoms, whereinthe aromatic organic group exists alone, two or more aromatic organicgroups are bonded to each other to form a divalent condensed ring, ortwo or more of the aromatic organic groups are linked by a single bond,a fluorenyl group, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—,—(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—,—C(CF₃)₂—, or —C(═O)NH—; E¹¹, E¹², and E¹³ are each independently asingle bond or —NH—; and each Z¹⁰ is the same as or different from eachother in each repeating unit, and each represents a trivalent linkinggroup derived from one or more compounds selected from the groupconsisting of triacyl halide, tricarboxylic acid, and tricarboxylate,*E²¹-Y²⁰-E²²-Z²⁰-E²³*  [Chemical Formula 2] wherein, in the ChemicalFormula 2, each Y²⁰ is the same as or different from each other in eachrepeating unit, and each independently includes a divalent aromaticorganic group having 6 to 30 carbon atoms, wherein the aromatic organicgroup exists alone, two or more of the aromatic organic groups arebonded to each other to form a divalent condensed ring, or two or moreof the aromatic organic groups are linked by a single bond, a fluorenylgroup, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)—(wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or—C(═O)NH—; E²¹, E²², and E²³ are each independently a single bond or—NH—; each Z²⁰ is the same as or different from each other in eachrepeating unit, and each is a divalent linking group in the form of—C(═O)-A-C(═O) derived from one or more compounds selected from thegroup consisting of diacyl halide, dicarboxylic acid, and dicarboxylate;in Z²⁰, A is a divalent aromatic organic group having 6 to 20 carbonatoms, a divalent heteroaromatic organic group having 4 to 20 carbonatoms, a divalent alicyclic organic group having 6 to 20 carbon atoms,or a divalent organic group in which two or more of the organic groupsare linked by a single bond, a fluorenyl group, —O—, —S—, —C(═O)—,—CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10),—(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—; and inZ₂₀, two carbonyl groups connected to both sides of A are bonded at ameta position to each other with respect to A.
 6. The polyamide-imideresin film according to claim 5, wherein the first repeating unitincludes a repeating unit represented by Chemical Formula 1-a:

wherein, in the Chemical Formula 1-a, each R¹¹ is the same as ordifferent from each other in each repeating unit, and each independentlyrepresents a single bond, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—,—Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10),—C(CH₃)₂—, —C(CF₃)₂—, —C(═O)NH—, or a divalent aromatic organic grouphaving 6 to 30 carbon atoms; R¹² and R¹⁴ each independently represent—H, —F, —Cl, —Br, —I, —CF₃, —CCl₃, —CBr₃, —CI₃, —NO₂, —CN, —COCH₃,—CO₂C₂H₅, a silyl group having three aliphatic organic groups having 1to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbonatoms, or an aromatic organic group having 6 to 20 carbon atoms; eachR¹³ is the same as or different from each other in each repeating unit,and each independently represents a single bond, a fluorenyl group, —O—,—S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or—C(═O)NH—; n1 and ml are each independently an integer of 0 to 3; n2 andm2 are each independently an integer of 1 to 4; E¹¹, E¹², and E¹³ areeach independently a single bond or —NH—; and each Z¹⁰ is the same as ordifferent from each other in each repeating unit, and each represents atrivalent linking group derived from one or more compounds selected fromthe group consisting of triacyl halide, tricarboxylic acid, andtricarboxylate.
 7. The polyamide-imide resin film according to claim 6,wherein: R¹¹ and R¹³ are the same as or different from each other ineach repeating unit, and each independently represents a single bond or—C(CF₃)₂—; Z¹⁰ is a trivalent linking group derived from one or morecompounds which are selected from the group consisting of1,3,5-benzenetricarbonyl trichloride, 1,2,4-benzenetricarbonyltrichloride, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylicacid, trimethyl 1,3,5-benzenetricarboxylate, and trimethyl1,2,4-benzenetricarboxylate.
 8. The polyamide-imide resin film accordingto claim 5, wherein the first repeating unit includes a repeating unitrepresented by Chemical Formulae 1-b 1-c:

wherein, in the Chemical Formulae 1-b and 1-c, R¹² and R¹⁴ independentlyrepresent —H, —F, —Cl, —Br, —I, —CF₃, —CCl₃, —CBr₃, —CI₃, —NO₂, —CN,—COCH₃, —CO₂C₂H₅, a silyl group having three aliphatic organic groupshaving 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;n1 and ml are each independently an integer of 0 to 3; and n2 and m2 areeach independently an integer of 1 to
 4. 9. The polyamide-imide resinfilm according to claim 5, wherein Z²⁰ is a group selected from thegroup consisting of the following structural formulas:

wherein, in the above structural Formulae, R²¹ is —H, —F, —Cl, —Br, —I,a silyl group having three aliphatic organic groups having 1 to 10carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, oran aromatic organic group having 6 to 20 carbon atoms, a1 is an integerof 0 to 3, and a2 is an integer of 0 to
 2. 10. The polyamide-imide resinfilm according to claim 5, wherein the second repeating unit includes arepeating group represented by Chemical Formula 2-a:

wherein, in the Chemical Formula 2-a, each R²² is the same as ordifferent from each other in each repeating unit, and each independentlyrepresents a single bond, a fluorenyl group, —O—, —S—, —C(═O)—,—CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10),—(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—; eachR²³ independently represents —H, —F, —Cl, —Br, —I, —CF₃, —CCl₃, —CBr₃,—CI₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silyl group having three aliphaticorganic groups having 1 to 10 carbon atoms, an aliphatic organic grouphaving 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20carbon atoms; n3 and m3 are each independently an integer of 1 to 4;E²¹, E²², and E³ are each independently a single bond or —NH—; and Z²⁰is a group selected from the group represented by the followingstructural Formulae:


11. The polyamide-imide resin film according to claim 5, wherein thesecond repeating unit includes a repeating group represented by ChemicalFormula 2-b:

wherein, in the Chemical Formula 2-b, each R²³ is independently —H, —F,—Cl, —Br, —I, —CF₃, —CCl₃, —CBr₃, —CI₃, —NO₂, —CN, —COCH₃, —CO₂C₂H₅, asilyl group having three aliphatic organic groups having 1 to 10 carbonatoms, an aliphatic organic group having 1 to 10 carbon atoms, or anaromatic organic group having 6 to 20 carbon atoms; and n3 and m3 areeach independently an integer of 1 to
 4. 12. The polyamide-imide resinfilm according to claim 5, wherein the polyamide-imide block copolymerfurther includes a third repeating unit represented by Chemical Formula3:*E³¹-Y³⁰-E³²-Z³⁰-E³³*  [Chemical Formula 3] wherein, in the ChemicalFormula 3, each Y³⁰ is the same as or different from each other in eachrepeating unit, and each independently includes a divalent aromaticorganic group having 6 to 30 carbon atoms, wherein the aromatic organicgroup exists alone, two or more of the aromatic organic groups arebonded to each other to form a divalent condensed ring, or two or moreof the aromatic organic groups are linked by a single bond, a fluorenylgroup, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)—(wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or—C(═O)NH—; E³¹, E³², and E³³ are each independently a single bond or—NH—; each Z³⁰ is the same as or different from each other in eachrepeating unit, and each is a divalent linking group in the form of—C(═O)-A-C(═O)— derived from one or more compounds selected from thegroup consisting of diacyl halide, dicarboxylic acid, and dicarboxylate;in Z³⁰, A is a divalent aromatic organic group having 6 to 20 carbonatoms, a divalent heteroaromatic organic group having 4 to 20 carbonatoms, a divalent alicyclic organic group having 6 to 20 carbon atoms,or a divalent organic group in which two or more of the organic groupsare linked by a single bond, a fluorenyl group, —O—, —S—, —C(═O)—,—CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10),—(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—; and inZ₃₀, two carbonyl groups connected to both sides of A are bonded at apara position to each other with respect to A.
 13. The polyamide-imideresin film according to claim 12, wherein Z³⁰ is a group selected fromthe group consisting of the following structural Formulae:

wherein, in the above structural Formulae, R³¹ and R³² are eachindependently —H, —F, —Cl, —Br, —I, a silyl group having three aliphaticorganic groups having 1 to 10 carbon atoms, an aliphatic organic grouphaving 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20carbon atoms; b1 and b2 are each independently an integer of 0 to 3; andb3 is an integer of 0 to
 2. 14. The polyamide-imide resin film accordingto claim 12, wherein the third repeating unit includes a repeating unitrepresented by Chemical Formula 3-a:

wherein, in the Chemical Formula 3-a, each R³³ is the same as ordifferent from each other in each repeating unit, and each independentlyrepresents a single bond, a fluorenyl group, —O—, —S—, —C(═O)—,—CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—, —(CH₂)_(p)— (wherein 1≤p≤10),—(CF₂)_(q)— (wherein 1≤q≤10), —C(CH₃)₂—, —C(CF₃)₂—, or —C(═O)NH—; eachR³⁴ is independently —H, —F, —Cl, —Br, —I, —CF₃, —CCl₃, —CBr₃, —CI₃,—NO₂, —CN, —COCH₃, —CO₂C₂H₅, a silyl group having three aliphaticorganic groups having 1 to 10 carbon atoms, an aliphatic organic grouphaving 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20carbon atoms; n4 and m4 are each independently an integer of 1 to 4;E³¹, E³², and E³³ are each independently a single bond or —NH—; and Z³⁰is a group selected from the group represented by the followingstructural Formulae:


15. The polyamide-imide resin film according to claim 12, wherein thethird repeating unit includes a repeating unit represented by ChemicalFormulae 3-b or 3-c:

wherein, in the Chemical Formulae 3-b and 3-c, each R³⁴ is independently—H, —F, —Cl, —Br, —I, —CF₃, —CCl₃, —CBr₃, —CI₃, —NO₂, —CN, —COCH₃,—CO₂C₂H₅, a silyl group having three aliphatic organic groups having 1to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbonatoms, or an aromatic organic group having 6 to 20 carbon atoms; and n4and m4 are each independently an integer of 1 to
 4. 16. Thepolyamide-imide resin film according to claim 12, wherein a molar ratioof the third repeating unit to the second repeating unit is 0.5 to 3.